1. Field of the Invention
This invention relates to an improved composition comprising a mixture of toasted soybean flakes and potato flakes, for making a highly soy protein enriched and soy oil containing mashed potato product exhibiting excellent nutritional, taste and texture properties. The toasted soybean flakes are prepared from full fat, enzyme active soybean flakes, which are made from dehulled soybeans. The toasted soybean flakes are made by heating the full fat, enzyme active soybean flakes in hot fluidizing gas at a temperature and for a time sufficient to substantially eliminate beany or other off-flavors, without significant denaturing of the soybean protein. The invention further relates to method for making said highly soy protein enriched mashed potato product from said composition; and to said mashed potato product per se. The toasted soybean flakes used in the present invention permit use of soybeans varieties other than the null varieties, especially triple null, which are expensive and generally believed necessary to avoid undesirable beany flavors associated with untoasted flakes.
2. Background and Description of Related Art
Soybeans have long been a staple of the Asian diet in multiple food forms including tofu and soymilk, among many other soy based and fermented foods. Soybeans are excellent sources of protein. Enzyme active soy protein, i.e., soy protein which has not been denatured, has a desirable amino acid profile for nutritional purposes, and includes other health promoting elements such as phytoestrogens. In recent years, demand for soy foods has grown dramatically in the United States and other western countries, principally in the form of meat analogues, nutrition bars and powdered nutrition beverages prepared from soy protein isolates and concentrates. Chemically fractionated soy ingredients and soymilk are prepared by modernized methods to reduce much of the traditional “beany” flavor favored in the East, but severely objected to in the West. Demand for natural and organic foods has grown at an extraordinary rate. Foods designated “natural” and/or “organic” generally cannot utilize chemically processed materials. The soy ingredients commonly used today are not full fat or oil, having been treated with solvents such as hexane to remove fats or oils. The terms “fat” and “oil” are used interchangeably with respect to soybeans in the prior art and in this application. The defatted concentrates or isolates do not qualify as natural or organic, as has been increasingly popular in today's market. U.S. Pat. Nos. 6,495,140 and 6,426,111, for example, illustrate preparation of soy fractionates and/or isolates using solvent extraction.
The soybean flakes useful for making the toasted soybean flakes used in the present invention are made from full fat, enzyme active, dehulled soybeans, such as by the method recited in U.S. Pat. No. 4,895,730. This patent is hereby incorporated herein by reference, and is assigned to MicroSoy Corporation, 300 East MicroSoy Drive, Jefferson, Iowa 50129. Soybean flakes made from full fat, enzyme active, dehulled soybeans, by the method of the '730 patent are called MicroSoy Flakes® and are denoted herein as “MSF” in the COMPARATIVE EXAMPLES and as “MX” in TABLE 1. The soybean flakes used in the present invention qualify as “natural”; and when prepared from soybeans qualifying as organically grown, also qualify as organic foodstuffs.
Full fat, enzyme active (i.e., wherein the proteins are undenatured), dehulled soybeans are excellent sources of elements necessary for good health, and supply outstanding nutritional and nutraceutical benefits. Undenatured soybeans and soybean flakes are excellent sources of protein, iron, vitamin-B, calcium, lecithin and isoflavones. In particular, the lecithin content is from about 2.7 to 3.1 percent. Soybeans also contain essential minerals including phosphorus, which is an essential element used by the body for building bones. Soy isoflavones are now considered helpful in reducing risks for cancer, heart disease, and osteoporosis. Pure soya contains about 38-42% protein, 18-22% fat or oil (of this lecithin is 2.7-3.1%), 25-35% carbohydrate, 1.5-2.5% minerals, 3-5% fiber, and 5-6% water. Full soya flour furnishes about 89 grams of protein per 1000 calories, i.e., about 132 grams of protein and 44 grams oil per 1000 grams. By contrast potatoes contain only about 21 grams of protein per 1,000 calories. In addition, since soybeans do not contain particular glutens, products containing substantial amounts of soybeans offer an alternative for people suffering from celiac disease and/or gluten allergies. Full soya flour contains about three times the grams of protein per 1000 grams as lean beef. A “typical analysis of soy flour and soy grits appears in “The Soybean Digest”, Vol. 19, No. 8, June 1959, pages 8 to 9, as follows:
FullHighLowfat/oilfat/oilfat/oilDefattedProtein, %40.045.048.052.0Fat, %20.015.05.00.5Fiber, %2.52.53.03.0Ash, %5.05.05.56.5Moisture, %8.08.08.08.0MicroSoy® full fat, enzyme active soybean flakes contain 40-48% protein, 19.0% fat/oil, 2.1% fiber, 4.79% ash, 8.08% moisture, and 27.59% carbohydrate.
There exists in the prior art need for soy protein enriched products, while maintaining good taste, texture, and processibility in standard food processing equipment. The present inventors and the prior art faced the problem that unfortunately products containing large amounts of soybeans tend to exhibit undesirable taste and/or texture properties. They also faced the problem that amounts of soybean flakes which could be used in various compositions was limited by beany and other objectionable flavors incurred at higher soybean flake concentrations; thus, requiring at higher concentrations the use of expensive triple null variety soybeans. This was especially true of soybean flakes-potato flakes compositions, such as disclosed in parent patent application Ser. No. 10-382,697, where the amount of soybean flakes was limited to 45%, by the occurrence of beany flavors at higher amounts.
U.S. patent application Ser. No. 10-382,697 was filed Mar. 6, 2003 in the names of inventors Itaru Tanaka, Safir Moizuddin, and Bruce Liu; and titled COMPOSITION CONTAINING SOYBEAN FLAKES AND POTATO FLAKES, METHOD FOR MAKING A FOOD PRODUCT THEREFROM, AND SAID FOOD PRODUCT; now pending. This patent application is, of course, incorporated herein by reference.
The present inventors faced the problem that null variety soybeans, especially the expensive triple null, were required at higher soybean flakes concentrations to avoid beany flavors. There was clearly a need for soybean flakes which could be made with a wide range of soybean varieties without incurring objectionable beany flavors. Products containing large amounts of soy materials, in addition to beany flavors, also exhibit unpleasant characteristics including beany flavors, chalkiness and/or mouth dryness, grittiness, grassy flavor, bitter flavor, salty flavor, and astringency. Moreover, the present inventors and the prior art faced the problem that soybeans do not contain certain proteins, such as prolamins, gliadin or glutenin, nor sufficient starches, that provide elasticity, cohesiveness and binding during processing.
U.S. patent application Ser. No. 10/793,238, has been filed on even date herewith in the name of inventors Itaru Tanaka and Safir Moizuddin, and is titled TOASTED SOYBEAN FLAKES AND METHOD OF MAKING SAME, now U.S. Pat. No. 7,169,432. This application is hereby incorporated herein by reference; and will be referred to hereinafter as the “copending ‘TOASTED SOYBEAN FLAKES . . . ’ application”.
The present inventors discovered, as disclosed in detail in the copending “TOASTED SOYBEAN FLAKES . . . ” application, a method of preparing toasted soybean flakes which significantly reduces and/or eliminates the beany or off-flavors associated with soy materials, while minimizing denaturing of soy proteins. The inventive toasted flakes are made by heating, in a hot fluidizing gas, fill fat, enzyme active soybean flakes, prepared from dehulled soybeans, to a temperature and for a time sufficient to substantially eliminate objectionable beany and off-flavors, while avoiding denaturing of the soy protein.
The present inventors have discovered that unexpectedly higher amounts of the inventive toasted soybean flakes can be incorporated into soybean flakes-potato flakes compositions useful for making highly soy protein enriched and soy oil containing mashed potato products, while maintaining excellent taste and texture and avoiding objectionable beany flavors. Soybean flakes-potato flake compositions are disclosed in parent U.S. patent application Ser. No. 10-382,697, as limited to a maximum soybean flake content of 45%, without incurring objectionable beany flavors. Use of toasted soybean flakes unexpectedly permits, contrary to the maximum of 45% soybean flakes taught in the '697 application, inclusion of up to 60% toasted soybean flakes, while avoiding beany flavors and retaining excellent flavor and texture. The '697 application teaches that amounts higher than 45%, even with soybean flakes made from triple null soybean varieties, result in undesirable beany flavors and other changes in taste and texture. The inventive toasted soybean flakes permit use of soybeans varieties other than the null varieties, especially triple null, which are expensive and usually thought to be required to avoid undesirable beany flavors associated with use of untoasted flakes.
Moreover, as discussed in the '697 application, the average serving of potato (one medium potato or about 148 grams) contains only 3 grams of protein. There is a need for a mashed potato product having significantly increased protein content, without negatively affecting the consumer acceptance thereof, and to make the health claim of providing a minimum of 6.25 grams of soy protein per serving. Additionally, potato products, such as mashed potatoes containing 100% potatoes, are known in the art to exhibit a bland starchy taste and pasty feel. This is due in part to the fact that potatoes contain large amounts of starch, and little or no fat or oil. Moreover, potato is in the nightshade family and suspect in certain arthritic maladies. Soybean flakes-potato flakes compositions made possible by the present invention contain significantly reduced amounts of potato and higher amounts of soybean flakes than previously thought possible.
The present inventors have discovered that toasting full fat, enzyme active soybean flakes made from mechanically dehulled soybeans permits unexpectedly high amounts of up to about 60% toasted soybean flakes to be incorporated into soybean flakes-potato flakes compositions, with excellent flavor and texture retention. The toasted soybean flakes-potato flakes products made from the present inventive compositions avoid the expected problems of undesirable beany flavors, and other objectionable changes in taste and texture. Use of toasted soybean flakes unexpectedly results in a soy protein enriched and soy oil containing mashed potato products, which are not beany flavored and have excellent nutritional, taste and texture properties.
Prior Art Relating to Soy-potato Mixtures:
Addition of small amounts of soya flour to mashed potatoes was mentioned as early as 1941 (The Soybean Digest, Vol. 2, No. 9, December 1941, pages 2 to 5).
U.S. Pat. No. 4,005,139 illustrates dehydrated potato solids in the form of flakes, granules and/powder, and containing various additives, binders, fillers, gums, and texturizing agents, in which the potato portion constitutes at least 50% of the mixture. The dehydrated potato solids are disclosed to be formed into slurry or dough, and used subsequently for preparing products suitable for deep frying.
U.S. Pat. No. 6,066,353 illustrates dehydrated potato flakes prepared from potato slices, slivers and/or nubbins, which flakes are used to prepare more cohesive, non-sticking, machinable dough compositions.
U.S. Pat. No. 6,235,333 illustrates a sheetable dough composition useful for making fried snack pieces. The sheetable dough composition is disclosed to comprise about 50% to about 70% of a starch-based material, wherein said starch-based material comprises from about 25% to about 100% dehydrated potato flakes. U.S. Pat. No. 6,235,333 further indicates that the starch-based material may contain other ingredients including potato flour, tapioca flour, peanut flour, wheat flower, oat flour, rice flour, corn flour, soy meal, corn meal, potato starch, tapioca starch, corn starch, oat starch, cassava starch and mixtures thereof.
U.S. Pat. No. 6,287,622 similarly discloses 30-60% “other starch” such as soy meal. U.S. Pat. No. 3,911,142 illustrates a ready-to-eat snack type wafer made by dry mixing potato flakes and various ingredients including soy protein, blending with water, followed by sheeting or extruding, and then baking or frying.
U.S. Pat. No. 3,950,550 shows making a fried tofu product by forming a kneaded soy dough, which may contain potato starch, into a desired shape, and deep frying the shaped material in two successive stages.
U.S. Pat. No. 6,479,089 illustrates a cohesive soy based machinable dough comprising soy grits and potato starch as one of the additional ingredients.
U.S. Pat. No. 6,177,116 discloses a dough composition useful for preparing fried chips, which composition is a starched-based material comprising from about 40% to about 90% combined potato flakes and granules, and from about 10% to about 60% of other starch containing ingredients selected from potato flour, tapioca flour, peanut flour, wheat flour, oat flour, rice flour, corn flour, soy meal, corn meal, potato starch, tapioca starch, cornstarch, oat starch, cassava starch, and mixtures thereof.
U.S. Pat. No. 6,291,009 teaches making chips or crackers using soy flour and potato flour. U.S. Pat. No. 5,866,192 discloses preparation of an edible material containing soybean walls purported to have a good taste and mouthfeel, and useful similarly to soybean jam or mashed potato.
Japanese Patent document #53-133657, dated Nov. 28, 1978, illustrates a method comprising kneading with water a dry potato powder mixture, containing added gluten powder, optionally together with 1% or more soybean protein powder, dry egg white powder, polysaccharide and starch; followed by molding the obtained dough into suitable form, and frying it in suitable oil.
Japanese Patent document 44-11594 (1969) illustrates a method of producing soybean paste powder that can be suitably crushed and treated, characterized by adding 3% to 25% steamed potato or dried mashed potato flake to uncooked soybean paste and drying using a single drum dryer.
Japanese Patent Publication #07-227239, published Aug. 29, 1995, shows imitation potato made by gelling a mixture of potato flakes and vegetable fibers (e.g., the vegetable fibers of soybean flour), to which a gelling agent has been added.
Prior Art Relating To Heat Treating Soy Materials:
Roasting of soy materials to reduce beany or off-flavors has been generally known in the prior art, as illustrated by U.S. Pat. Nos. 5,936,069 and 3,971,856 (see second paragraph of Description). However, the prior art roasting procedures have generally been carried out, not on full fat, enzyme active soybean flakes made from dehulled soybeans, but on defatted or chemically treated or otherwise prepared soy materials. Furthermore, the roasting processes of the prior art have generally been carried out by heating methods other than used in making the toasted soybean flakes of the present invention, and at temperatures and conditions causing significant denaturing of the soy proteins. Moreover, the toasted soybean flakes used in the present invention differ variously from the prior art in that the starting soybean flakes are not defatted or chemically treated, or steam heated, or made from soybean meal or flour. The reduction of the soybean material in the prior art to meal or flour significantly increases its exposure to oxidation and results in generation of off-flavors and denaturizaton of the soy proteins.
In the present invention, the toasted soybean flakes are prepared from the full fat, enzyme active soybean flakes made from dehulled soybeans. The soybean flakes used to prepare the toasted soybean flakes of the present invention are preferably made by the method shown in U.S. Pat. No. 4,895,730, which patent is incorporated herein by reference. The toasted flakes are prepared by subjecting the full fat, enzyme active soybean flakes quickly to blown fluidizing dry air heat while moving on and/or above a vibrating surface.
U.S. Pat. No. 6,391,374 is teaches pretoasting defatted soy flakes to reduce the bittery or beany off-flavors of the soybean due to lipid peroxidation catalyzed by lipoxygenase.
U.S. Pat. No. 3,971,856 illustrates subjecting dehulled, cracked soybeans to water at 180° F. to a maximum of 212° F. to eliminate any toasting of the soybeans.
U.S. Pat. No. 4,810,513 shows making full fat soybeans flakes from raw soybeans with hulls intact, including the step of drying the flakes in a forced air drier by alternating application of superheated air.
U.S. Pat. No. 4,041,187 illustrates heating tenderized soybean cotyledons sufficiently, such as in an air drier at 200° F. for five minutes, to deactivate the lipoxygenase enzymes.
U.S. Pat. No. 3,941,890 illustrates making soy milk including cooking soybeans in a microwave oven for a time sufficient to destroy the trypsin inhibitor and eliminate any unpleasant beany taste, but for a time insufficient to roast the material.
U.S. Pat. No. 4,103,034 illustrates preparing dried flaked textured vegetable protein from defatted or full-fat soybean flour, which has been dried at temperatures which assure partial or substantial deembitterment without scorching. The '034 Patent discusses toasting carried out preferably between 180 and 200° F. for preferably between 1.5 and 2.5 hours, using hot dry air (page 12).
U.S. Pat. No. 5,710,365 teaches heat treating de-oiled (defatted) soybean flakes to denature the protein therein.
U.S. Pat. No. 4,748,038 illustrates subjecting whole or dehulled and split soybeans to live steam or water for a time sufficient to avoid green, painty or raw flavors developing and short enough such that beany or bitter flavors do not develop.
U.S. Pat. No. 4,409,256 shows making soymilk involving comminuting whole soybeans having the hulls on, forming a slurry and simultaneously heating by an infusion of live steam initiating inactivation of trypsin inhibitor and lipoxygenase without fixing or substantially denaturing the soybean protein.
U.S. Pat. No. 4,639,216 shows flame roasting cereal grains including soybeans to destroy toxic enzymes in the raw soybeans which interfere with digestion and growth in animals, and to sterilize the grain.
U.S. Pat. No. 4,923,710 shows roasting deskinned and split soybean halves which have been soaked for swelling and then dewatered.